The present invention is related to a spraying apparatus for forming low-melting-point metal mold. The spraying apparatus includes a spraying system and a cooperative adjustment seat for performing the spraying operation to form the low-melting-point metal mold. The molten metal is directly sprayed onto the surface of the model many times to form a metal coating thereon without contraction. The mold is made by means of many times of spraying operation so that the mold will not deform due to internal stress. The low-melting-point metal mold is free from the problems of contraction and deformation. In addition, the mold can be more quickly made at higher precision. Also, when not used, the low-melting-point metal molds can be recovered and molten into liquid metal for reuse. (The recovery ratio is up to 80˜95%.) The low-melting-point metal mold will not lead to any environmental problem due to the resin mixed with the metal.
A conventional low-melting-point metal fast mold is manufactured according to casting principles. The low-melting-point metal is first heated and molten. Then the molten metal is directly poured into a plaster mold or ceramic mold. After the molten metal is cooled and solidified, a fast metal mold is obtained. Such manufacturing method has some shortcomings as follows:                1. During the transfer manufacturing procedure, the plaster or ceramic mold will contract and deform.        2. In the casting operation, a cooling apparatus is arranged for cooling the molten metal. However, such cooling apparatus can hardly fully evenly cool the molten metal. Therefore, the stress will concentrate on a certain part of the mold to lead to deformation of the mold.        3. It takes a considerably long time to manufacture the mold so that the manufacturing cost is relatively high. It takes about two days to transfer manufacture the fast metal mold with a plaster mold. It takes about 3˜5 days to transfer manufacture the fast metal mold with a ceramic mold.        
There is another measure for manufacturing the low-melting-point metal fast mold. The middle-melting-point zinc alloy wire material is positioned between the positive and negative electrodes of an electric arc gun. The zinc alloy wire material is molten by high electric arc. At the same time, by means of high-pressure air, the molten metal is atomized to adhere to the surface of the mold to form the fast metal mold. Such technique has some shortcomings as follows:                1. The working environment is dangerous and hard. High voltage power is used to melt the zinc alloy (with a high melting point of about 430° C.). Therefore, the work is dangerous. In addition, the high-pressure gas and the high-voltage electric arc cause great noise in the working site. Therefore, the working environment is very hard.        2. The mold has poor precision and serious deformation. Due to the high temperature, high stress and great contraction ratio of the zinc alloy (1%˜1.1%), the demolding face and the mold-dividing face of the mold often deform seriously. The faces of the mold tend to have reverse hooks. In addition, it often takes place that the mold sections cannot be truly mated. Therefore, such technique is only applicable to those molds without high requirement for precision and free from the demolding problem, such as the molds for injection molding soft products of rubber material, for example, sole, tire, etc.        3. The mold lamination speed is slow so that it takes long time to manufacture the mold. In general, only a mold shell with a thickness within 1 mm˜2 mm is made. Then the mold shell is filled with a metal resin backup material. Such mold includes metal and unrecoverable thermosetting metal resin mixed with the metal. The bonding between the metal and the resin is poor. In addition, such mold will cause the problem of environmental protection.        